General Alexander Mackay

v. Alexander Mackay, had an Ensign's commission in the 25th Foot in 1737, raised an independent company for Loudon's regiment in 1745, and was taken prisoner at Prestonpans. But. ms. He became Major of the 3rd Foot in 1750, and Colonel of the 52nd Foot in 1755. He became M.P. for Sutherland in 1761, but some time thereafter went to America with his regiment and rose to the rank of Major-General. He was elected M.P. for the Northern Burghs in 1773, and appointed Governor of Tynemouth Fort in 1772. In 1780 he became Commander-in-Chief of the forces in Scotland, and Governor of Stirling Castle in 1788.

He married in 1770, Margaret, daughter of Sir William Carr of Etal, Bart., and ''' died without issue, 31st May, 1789.''' pg. 194 

THE BOOK OF MACKAY BY ANGUS MACKAY, M.A. (St. Andrews University) Minister at Westerdale, Caithness EDINBURGH : NORMAN MACLEOD, -25 GEORGE IV. BRIDGE CANADA : EDWARD MACKAY, ST. PETER'S MANSE, MADOC,

ONT. M DCCCC VI

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Alexander, raised an independent company for Loudon's Highlanders in 1745, and was taken prisoner at Prestonpans ; became M.P. for Sutherland 1761, and ommander-in-chief of the Forces in Scotland in 1780.

He married, at Porde, 24 December 1770, Margaret, daughter of Sir William Oarr of Etal, Bart., and died, without issue, 31 May 1789. She survived him, and married, secondly, 4 October 1792, James Farquharson of Invercauld.

Scottish Peerage pg. 175

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. Lt Gen Hon Alexander Mackay, raised an independent company for Loudoun's Highlanders 1745, captured at the Battle of Prestonpans 1745, Member of Parliament for Sutherland 1761, Commander-in-Chief of the Forces in Scotland 1780 (dsp. 31 May 1789),

mar. 24 Sec 1770 Margaret Carr (mar. (2) 4 Oct 1792  as his second wife James Farquharson of Invercauld),  dau. of Sir William Carr of Etal, Bt.

http://www.cracroftspeerage.co.uk/online/content/reay1628.htm